X is for XIntercept
by Lumosthecat
Summary: My response to the summer alphabet challenge.


**X is for X-intercept**

_Summary: My response to the alphabet challenge._

_Disclaimer: NUMB3RS is the creation of Cheryl Heuton and Nicolas Falacci and I have no legal rights to the characters and their backgrounds._

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Don was eight when his little brother could multiply four digit numbers in his head. He was 14 when he was told that Charlie would start high school with him. At 16, he was re-taking algebra in summer school while his 11 year old brother was taking university level calculus through a correspondence course from CalSci.

Sometimes, he thought to himself, life just wasn't fair.

He sat in the solarium, the sun shining brightly through the glass windows as he crumpled another piece of paper.

Stupid algebra. He couldn't stand it. Why he had to take it he would never know. No one ever used it. Unless you were Charlie.

What did it matter what the equation of a line was or how to find the x-intercept? It was stupid and useless.

He stared at the graph again, trying to figure out why he couldn't just read off of the numbers and write it in.

He stared outside again at the sunshine, annoyed that he had to spend the first half of his summer in a classroom and in the house, doing homework. He wanted to be outside playing baseball with his friends and practicing his swinging techniques. He still couldn't lay-off of the low and outside pitches.

He was never going to get a scholarship based on his math skills. But he knew baseball was his ticket out of this place and away from Charlie's shadow.

He heard the soft, hesitant footfalls of his younger brother as he tried to tip toe into the room where he was working.

"Charlie, leave me alone. I'm trying to do my homework. Some of us are being forced to go to school in the summer. Unlike some people." Don knew that he sounded bitter and petty, but he couldn't stop the words from coming out of his mouth.

"I just wanted to see if you wanted to throw the ball with me." Don turned to see his little brother carrying one of his old baseball mitts that was still too big for him.

"Can't you see I'm busy?" He said grouchily, the reminder that he couldn't go out and practice until he finished the problem set adding to his misery.

Charlie tentatively walked over to his brother. "Maybe I could help you."

"I don't need your help Charlie!" He said angrily, more out of shame that he needed his brother's help than anything else.

Charlie, frightened at Don's tone, backed away.

"Sorry, I just thought…"

"Listen, not everyone can do math like you can. It's harder for other people."

Charlie looked shocked at his words. "But you're not other people. You're Don."

Don bit back a retort, knowing that Charlie didn't mean anything bad by what had he said. It was a source of constant amazement to him that his genius younger brother honestly believed that it was Don that could do anything.

Don sighed. Asking for Charlie's help seemed inevitable. His summer school teacher was even worse then his regular teacher, going over the material so quickly that he hardly had a chance to scribble out the notes before he moved on to another topic.

"We're supposed to find the x-intercept for the equations. And I get how to do it and everything, and it's easy when the equation is for a straight line."

"The slope multiplied by x plus the intercept is equal to y".

"Yeah, that." He didn't know how his little brother, clueless when it came to things like remembering where he put his shoes, could rattle off equations like they were nothing.

"But it's when things get complicated that I just can't seem to get it."

Charlie, excited to be helping his brother in something he knew how to do, took a seat beside him and picked up his textbook.

"I'm doing problem 3.44 and… it's just so weird. I mean, look at it."

y (equals) x (exponent)3 + 2x(exponent)2 – x – 3

Charlie stared at the equation and mentally solved for the x-intercept in his head. He came up with the answer almost immediately. He wanted to grin and show his brother exactly how to do it, but Charlie, even though he wasn't always sensitive to other people, knew that Don would take it badly if he just spouted off the answer.

"Well, this one is different from a normal equation for a straight line."

"Yeah, it has all those exponent things."

Charlie nodded enthusiastically.

"So, you have to figure out how to find the x-intercept."

"Yeah, I substituted 0 for y, but I'm still left with all that other junk. How am I supposed to solve for x?"

Charlie hesitantly asked, "Did you try the quadratic equation?"

Don rolled his eyes. "Yeah, but, it doesn't work for this equation. See, the first x has an exponent 3."

Charlie thought hard about how he could explain to Don what he saw so clearly in his head.

"Don, do you remember those paintings we saw at that art museum mom dragged us to a few years ago? The ones we thought were so weird looking?"

Don, thrown off by the change in subject, nodded. "The abstract paintings, sure. We couldn't figure out what things were at first because they didn't look like what they were supposed to."

"Right, but we figured out eventually what most of them were. Do you remember how we did it?"

Don looked at Charlie as if he had grown three heads. "Mom explained it to us. You rearrange parts of the painting and put them back together in our heads to reveal what they really are. Charlie, where are you going with this?"

"Well, this is the same thing. See, when you did this problem, you got hung up on the fact that one of the x's was to the exponent three."

Don nodded slowly. "And the quadratic equation only works when it's in the x-squared plus x plus some number form."

"So what you have to do is look at this equation and change it so that it looks like what you think it should look like. See, if you move this three to the other side, and factor out one of the x's on this side…"

Charlie couldn't help but smile when Don started to nod more quickly and grabbed the pencil. He began to mumble to himself. "If I take this x out, I'm left with x(exponent)2 + 2x – 1 and I can use the quadratic equation." Don grabbed his calculator and started to punch numbers. "I get two values for x and then I plug it in and…" He stopped suddenly and groped for the textbook, flipping to the back where the answers were.

"Ha! I actually got it!"

His face flushed, he looked at his younger brother who was happily beaming up at him.

"Thanks, Charlie. I don't know why I didn't see it before."

"You probably did but just let yourself get frustrated. I do it all of the time."

"Not with math you don't." Don said, without his usual resentment.

"Yeah, I do. There are problems people consider unsolvable, Don. I've been working on this one, P vs. NP, and every time I think I'm getting somewhere, it stops making sense to me."

Don dropped his pencil in surprise. "Really?"

Charlie nodded, slapping his hand against Don's old baseball mitt, which he still had clutched in his hand. "Yeah. Really. Not everything is easy for me."

Don looked at the top of his brother's head and marveled at the fact that he never gave him credit for things and just assumed that it all made sense to him.

Knowing the best way to make him feel better, he closed his book and nudged his brother's shoulder.

"Come on, I'm all done here. I'm going to grab my mitt and we can toss the ball around. I'll show you the curve ball I've been working on."

Charlie looked up, his eyes shining. "I thought you were going to practice with your friends at the baseball diamond this afternoon."

"Why would I want to do that when you're standing right in front of me? Come on, let's go."

Charlie followed his brother as he ran through the front door and Don grabbed his glove on the way out.

"You have the ball, Charlie?"

"Yeah, it's right here."

Charlie picked up his pace and managed to catch up with his brother's longer strides.

They spent most of that afternoon throwing the ball back and forth and Don giving Charlie pointers on how to swing the bat properly.

At the end of the day, when their mom called them in for dinner, Don sat at the table and stared at his brother. Maybe Charlie and he were different when it came to math and it sometimes got in the way of how they related to one another, but when he took it out of the equation, everything fell into place.

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A/N: I hope that I did the math correctly. It's been some time since I last tried to do algebra, but it made sense in my head at 1 in the morning. The equation looks a little weird butI didn't know how to convey exponents in this type of text field, so I apologize for the formatting. I hope you enjoyed it!


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